Ranunculaceae

Herbs, sometimes woody or herbaceous climbers or low shrubs, perennial or annual, often rhizomatous. Stems unarmed. Leaves usually basal and cauline, alternate or sometimes opposite, rarely whorled, simple or variously compound; stipules present or absent; petioles usually present, often proximally sheathing. Leaf blade undivided or more commonly divided or compound, base cordate, sometimes truncate or cuneate, margins entire, toothed, or incised; venation pinnate or palmate. Inflorescences terminal or axillary, racemes, cymes, umbels, panicles, or spikes, or flowers solitary, flowers pedicellate or sessile. Flowers bisexual, sometimes unisexual, inconspicuous or showy, radially or bilaterally symmetric; sepaloid bracteoles absent; perianth hypogynous; sepals usually imbricate, 3-6(-20), distinct, often petaloid and colored, occasionally spurred; petals 0-26, distinct (connate in Consolida), plane, cup-shaped, funnel-shaped, or spurred, conspicuous or greatly reduced; nectary usually present, rarely absent; stamens 5-many, distinct; anthers dehiscing longitudinally; staminodes absent (except in Aquilegia and Clematis); pistils 1-many; styles present or absent, often persistent in fruit as beak. Fruits achenes, follicles, or rarely utricles, capsules, or berries, often aggregated into globose to cylindric heads. Seeds 1-many per ovary, never stalked, not arillate; endosperm abundant; embryo usually small.

Distribution

Worldwide.

Discussion

Genera ca. 60, species 1700 (22 genera, 284 species in the flora).

The flowers of many species of Ranunculaceae begin to open long before anthesis, while the floral organs are just partly expanded. Only mature flowers with open anthers should be used for determination of diagnostic characteristics (especially measurements).

The literature is inconsistent about the term for the whorl of organs between sepals and stamens; these may be conspicuous and petaloid, or reduced to stalked nectaries, or intermediate between the two states. They have been called petals, honey-leaves, or (when they are inconspicuous) staminodes or nectaries. We follow M. Tamura (1993) and treat as petals all organs between the sepals and stamens, except in Clematis and Aquilegia where they usually bear rudimentary anthers and clearly represent staminodes.

Selected References

Brayshaw, T. C. 1989. Buttercups, Waterlilies, and Their Relatives (the Order Ranales) in British Columbia. Victoria. [Roy. Brit. Columbia Mus. Mem. 1.]

Duncan, T. and C. S. Keener. 1991. A classification of the Ranunculaceae with special reference to the Western Hemisphere. Phytologia 70: 24-27.

Tamura, M. 1963. Morphology, ecology and phylogeny of the Ranunculaceae I. Sci. Rep. Coll. Gen. Educ. Osaka Univ. 11: 115-126.

Tamura, M. 1993. Ranunculaceae. In: K. Kubitzki et al., eds. 1990+. The Families and Genera of Vascular Plants. 2+ vols. Berlin etc. Vol. 2, pp. 563-583.

Ziman, S. N. and C. S. Keener. 1989. A geographical analysis of the family Ranunculaceae. Ann. Missouri Bot. Gard. 76: 1012-1049.

Lower Taxa

Aconitum, Actaea, Adonis, Anemone, Aquilegia, Caltha, Cimicifuga, Clematis, Consolida, Coptis, Delphinium, Enemion, Eranthis, Helleborus, Hydrastis, Myosurus, Nigella, Ranunculus, Thalictrum, Trautvetteria, Trollius, Xanthorhiza

Illustrations

	Family ⠉	Taxon	Illustrator ⠉
	Ranunculaceae Ranunculaceae Ranunculaceae	Ranunculus acris Ranunculus pensylvanicus Hydrastis canadensis	John Myers John Myers John Myers
	Ranunculaceae Ranunculaceae Ranunculaceae	Ranunculus macauleyi Ranunculus sardous Ranunculus hebecarpus	John Myers John Myers John Myers
	Ranunculaceae Ranunculaceae Ranunculaceae	Ranunculus cardiophyllus Ranunculus abortivus Ranunculus eschscholtzii var. eschscholtzii	John Myers John Myers John Myers
... further results

Key

1	Flowers bilaterally symmetric; sepals showy; petals smaller than sepals.	> 2
1	Flowers radially symmetric; sepals showy or not; petals present or absent, smaller to larger than sepals.	> 4
2	Upper (adaxial) sepal (hood) saccate or helmet-shaped; petals completely hidden by sepals.	Aconitum
2	Upper (adaxial) sepal spurred; petals at least partly exserted from calyx.	> 3
3	Perennials; pistils 3(-5); petals 4, distinct.	Delphinium
3	Annuals; pistil 1; petals 2, connate.	Consolida
4	Fruits achenes or utricles; ovule 1 per pistil.	> 5
4	Fruits follicles, capsules, or berries; ovules 2 or more per pistil (1 of 2 aborting in Xanthorhiza, leaving 1 seed at maturity).	> 12
5	Sepals spurred; leaves all basal, blade linear or narrowly oblanceolate.	Myosurus
5	Sepals plane; leaves either not all basal, or blade not linear or narrowly oblanceolate.	> 6
6	Leaves all cauline and opposite; stems ±woody, at least at base.	Clematis
6	Leaves cauline and alternate (rarely opposite), or basal, or plants with basal leaves and opposite or whorled involucral bracts; stems herbaceous.	> 7
7	Plants with 1 or more pairs (opposite) or whorls of involucral bracts, these leaflike or calyxlike.	> 8
7	Plants without involucral bracts (inconspicuous, linear-lanceolate involucral bracts in Trautvetteria), cauline leaves if present alternate (rarely a pair of opposite, unlobed leaves in Ranunculus sect. Flammula).	> 9
8	Achenes with conspicuous veins or ribs on lateral surfaces; style absent.	Thalictrum thalictroides
8	Achenes without veins on lateral surfaces; style present.	Anemone
9	Petals absent; inflorescences panicles, racemes, or corymbs (umbels in Thalictrum thalictroides); filaments filiform or dilated distally.	> 10
9	Petals present (rarely absent in Ranunculus pedatifidus); inflorescences simple or compound cymes or flowers solitary; filaments filiform.	> 11
10	Leaves simple, blade lobed; flowers bisexual; inflorescences corymbs.	Trautvetteria
10	Leaves compound; flowers unisexual or bisexual; inflorescences panicles, racemes, corymbs, or umbels.	Thalictrum
11	Petals without nectaries; sepals 5(-8).	Adonis
11	Petals with basal nectaries; sepals 3-5(-6).	Ranunculus
12	Leaves dissected into linear, threadlike segments; pistils compound; fruits capsules.	Nigella
12	Leaves not dissected, if parted or compound the segments not linear; pistils simple; fruits aggregates of follicles or solitary or aggregate berries.	> 13
13	Shrubs; beak of follicle lateral, strongly incurved against abaxial surface of follicle.	Xanthorhiza
13	Herbs; beak of follicle, if present, terminal or nearly so, straight or slightly curved, sometimes hooked at tip.	> 14
14	Petals prominent, spurred.	Aquilegia
14	Petals if present inconspicuous, plane or funnel-shaped.	> 15
15	Flowers 12-50, in racemes or racemelike panicles.	> 16
15	Flowers 1-10, in leafy cymes or solitary.	> 17
16	Pistils 1-8; fruits follicles, usually aggregate; petals 2-cleft or absent.	Cimicifuga
16	Pistil 1; fruits berries; petals unlobed.	Actaea
17	Leaves simple, blade often lobed 1/2-3/4 its length, margins entire, crenate, or toothed; petals absent.	> 18
17	Leaves compound or divided to base; petals usually inconspicuous (absent in Enemion).	> 19
18	Leaf blades unlobed, margins entire, dentate, or crenate; fruits follicles.	Caltha
18	Leaf blades lobed, margins serrate; fruits berries.	Hydrastis
19	Leaves ternately 1-2× compound.	> 20
19	Leaves palmately or pedately compound or divided.	> 21
20	Leaves all basal; leaf blade deeply divided, ternately or pinnately 1-2× compound; petals present.	Coptis
20	Leaves basal and cauline; leaf blade ternately 2× compound; petals absent.	Enemion
21	Leaf segments lobed, margins sharply toothed; sepals persistent in fruit.	Helleborus
21	Leaf segments cleft or parted, margins entire or toothed; sepals not persistent in fruit.	> 22
22	Cauline leaves absent except for whorl of 3 involucral bracts immediately subtending flower; follicles stipitate.	Eranthis
22	Cauline leaves alternate, (0.8-)1 cm or more from flower, involucral whorl absent; follicles sessile.	Trollius